In general, a projection-type display or video projector displays an image that corresponds to a video signal upon a projection screen or other surface. Most modern devices are capable of correcting distortion, curves, focus, and other inconsistencies by way of manual controls. Traditionally, these video projection devices are widely used for business presentations, classroom training, home theater, etc. For example, projection devices are widely used in many schools and institutions to project onto an interactive white board during the course of teaching students.
Although projection-type display devices were initially developed to display presentations (e.g., business, education), today, these projection devices have become commonplace for home theaters. For example, many households today include home theaters specifically designed to view motion pictures upon a projection screen. These theaters are often equipped with a projection-type display device. Even though the cost of the devices has decreased to an affordable level, at least one difficulty remains with regard to consumer acceptance of the projection display device. This one reservation is that the projection bulbs typically used in projector are expensive lamps that have huge power consumption and a generally short life span. Thus, while the cost of the machine is affordable, maintenance is sometimes too expensive for many families to justify or afford.